WASHINGTON – Experts say eroding support for capital punishment in the United States is a key reason death sentences have fallen to a 30-year low this year and executions have hit the lowest level in a decade.

The analysts, and capital-punishment supporters and opponents, were reacting to the latest year-end report by the Death Penalty Information Center, a group that opposes execution.

It found there were 53 executions in 2006, the lowest number since 1996 – when there were 45 – and well below the high of 98 in 1999. There were 114 death sentences this year, the lowest level in 30 years and down from nearly 300 each year in the 1990s.

Reasons for the declines include plunging homicide rates, less public support for the death penalty and court rulings that outlawed executions of juvenile or mentally disabled criminals, the experts said.

“Support for the death penalty is on the decline, and more people are embracing the alternative sentence of life without parole,” said Richard Dieter, executive director of the center. “Capital punishment is risky, expensive and could result in irreversible error. Fewer people are now willing to put their faith in such a flawed policy.”

The decline in executions came as many states grappled with problems related to wrongful conviction and increased challenges arguing that lethal injection caused unnecessary and severe pain.

Florida Gov. Jeb Bush said Friday he would suspend executions after a medical examiner found that it took a condemned killer 34 minutes to die because the needles were inserted improperly.

In California, a federal judge ruled Friday that the state's method of execution using lethal injection was unconstitutional but could be fixed by changing the procedure.

James Alan Fox, a criminal-justice professor at Northeastern University in Boston, said the drop in executions and death sentences partly reflected changes in attitudes and slipping public support for the death penalty.

“Even supporters of the death penalty are worried about the potential for mistakes,” he said.

Fox cited the plunge in homicides in the United States, with the homicide rate dropping nearly 50 percent between 1993 and 2000. “When crime rates are low, like they are now, people are less apt to clamor for the death penalty,” he said.

Another factor for the declines could be the Supreme Court's decision in 2005 that abolished the death penalty for juveniles and its ruling in 2002 that barred the execution of mentally disabled criminals, Fox said.

The report said the number of death-row inmates decreased for the fifth consecutive year after 25 years of increases, declining to 3,366 in 2006 from 3,415 last year.

If the litigation over the use of lethal injections is resolved, the number of executions could rise in 2007, the report predicted.